-LRB- CNN -RRB- -- Syrian military airstrikes hit parts of the country 's largest city Thursday , killing at least 33 people and injuring several others , the UK-based opposition group Syrian Observatory for Human Rights said .

The airstrikes were the latest in a string of attacks reported in Aleppo , the northwest Syrian city that has been a hotly contested area in Syria 's civil war .

A day earlier , Syrian forces dropped barrel bombs on an opposition-held area of Aleppo , killing 25 children , according to the opposition Local Coordination Committees of Syria .

The unrest comes amid Syria 's three-year civil war pitting government forces against rebels trying to end the rule of Syrian President Bashar al-Assad .

The government intends to hold elections June 3 . Al-Assad , whose family has had a tight grip on power for 43 years , is running for another term .

The United Nations is asking the government to reconsider the election because of the war . More than 100,000 people , including many civilians , have been killed , according to the United Nations .

Al-Assad succeeded his father in 2000 and won a second term in 2007 , unopposed .

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Attacks come day after barrel bombs killed 25 children in Aleppo , according to opposition

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Syria 's largest city is a hotly contested area in civil war